The invention relates to a window blind with a winding shaft having a rolling-up device, a blind web rolled up on the winding shaft, and a pull bar, to which the free end of the blind web is fastened.
Window blinds of the type referred to, which serve as protection against the sun, particularly in vehicles, are generally designed as roller blinds and are correspondingly costly. Even more costly are electric motor-operated window blinds which also belong to the state of the art.
The object of the invention is to provide a window blind, in which the blind web can be drawn off the winding shaft and transferred into the sun protection position desired in a simple manner and locked, in particular a cost-effective design being sought.
Accordingly, the subject of the invention is a window blind with a winding shaft having a rolling-up device, a blind web rolled up on the winding shaft, a pull bar, to which the free end of the blind web is fastened, a guide device, on which the end regions of the pull bar are arranged longitudinally displaceably perpendicularly to the pull bar axis, and a braking arrangement which is arranged inside the pull bar and acts releasably on the guide arrangement in order to fix the pull bar in any positions on the guide arrangement. In this connection, the guide device preferably comprises two hollow profile strips which flank the blind web at its longitudinal edges and are each provided with a longitudinal slot on their mutually facing sides. However, rods, for example made of round material, can also be used instead of hollow profile strips. It is of great importance that closing bodies be inserted into the free ends of the pull bar. These engage in one of the longitudinal slots. Each slot has an opening with a brake block inserted in it, which is loaded by a compression spring. The brake blocks are arranged such that they can, via an adjustable connecting means, be moved toward one another counter to the force of the compression spring for canceling the braking action. As a rule, the brake blocks are located in pressing contact against the inner wall of the hollow profile strips, and this pressing contact is interrupted temporarily only for adjusting the blind web position.
Especially advantageously, the adjustable connecting means comprises a tautly guided wire cable which is fastened to the brake blocks and is supported by supports arranged at a spacing from one another. An actuating means acts on the wire cable arranged between the supports, and when that means is operated, it shortens the active length of the wire cable and draws the brake blocks toward one another. In this connection, the actuating means preferably comprises a manually operable lever which is articulated on the pull bar and supported on the wire cable by a working surface designed as an eccentric path.
In a development of the invention, the pull bar has a handle with a handle opening, in which the lever serving as the actuating means is arranged.
The invention also concerns a window blind with a winding shaft having a rolling-up arrangement, a blind web rolled up on the winding shaft, a pull bar, to which the free end of the blind web is fastened and a guide arrangement, on which the end regions of the pull bar are arranged longitudinally displaceably perpendicularly to the pull bar axis. The guide arrangement comprises two racks flanking the blind web at its longitudinal edges and two toothed wheels which mesh with the racks, and which are arranged in the end regions of the pull bar. At least one braking arrangement fixes the pull bar in any positions on the guide arrangement. The at least one braking device can act on one of the toothed wheels or a bearing shaft bearing a toothed wheel.
According to a preferred embodiment, the pull bar is provided in each end region with a bearing housing in each case surrounding a rack. Each bearing housing bears a toothed wheel arranged in a rotationally fixed manner on a bearing shaft. At least one of the bearing shafts is, for braking the restoring movement of the rolling-up arrangement, equipped with a friction brake which consists of a shaped body made of wear-resistant, viscoplastic synthetic material which is arranged in the bearing housing in a rotationally fixed manner in relation to the bearing shaft. The body has a bore for receiving an axial region of the bearing shaft. The diameter of the bore is smaller than the diameter of the bearing shaft, but sufficient to permit relative movement between the shaped body and the bearing shaft.
According to another preferred embodiment, a brake block loaded in each case by a compression spring in each case acts on untoothed circumferential regions of the toothed wheels. The arrangement of the brake blocks is effected in such a manner that they can, via an adjustable connecting means, be moved toward one another counter to the force of the compression spring, while canceling the braking action. The adjustable connecting means comprises a tautly guided wire cable which is fastened to the brake blocks and is supported by supports arranged at a spacing from one another. An actuating means acts on the wire cable arranged between the supports in order, when it is operated, to shorten the active length of the wire cable and to draw the brake blocks toward one another.
It is especially advantageous if the adjustable connecting means comprises a tautly guided wire cable which is fastened to the brake blocks and is supported by supports arranged at a spacing from one another. An actuating means acts on the wire cable arranged between the supports so that when it is operated, it shortens the active length of the wire cable and draws the brake blocks toward one another. The actuating means preferably comprises a manually operable lever which is articulated on the pull bar and supported on the wire cable by a working surface designed as an eccentric path. In this connection, the pull bar has a handle with a handle opening, in which the lever serving as actuating means is arranged.
According to a further preferred embodiment of the invention, at least one of the toothed wheels has, in addition to the toothing meshing with the rack, an external toothing. A braking body under the influence of a compression spring can be engaged in the tooth spaces. By means of a manually operable slide, the braking body disengaged again counter to the force of the compression spring.
In order to compensate possible dimensional differences of the spacing between the racks and the bearing housings, it is advantageous that at least one of the bearing housings is loaded outwardly, that is to say in the direction of a rack, by a compression spring.